#include<stdio.h>
int main()
{
    int sign = 1;
    double deno = 2.0,sum = 1.0,term;
    while(deno<=100){
        sign = -sign;
        term = sign/deno;
        sum = sum+term;
        deno = deno+1;
    }
    printf("%f\n",sum);
    return 0;
}